Dahlias are a colorful and versatile flower grown in home landscapes. Dahlias grow successfully as borders (either low or tall), in cutting gardens for use in floral arrangements and even in containers. Use large containers and quality soil to grow healthy, thriving dahlias. After a little tender loving care to get them started, dahlias will grow easily and abundantly.
Mix one part potting soil and two parts garden soil and fill the container approximately half way.
Place the dahlia tuber into the container, laying it horizontally. Add between 4 and 6 inches of additional potting soil above the tuber and pat it down firmly. Give the newly planted dahlia tuber a small amount of water.
Find a location for the container that receives morning sun and afternoon shade for best results. This will keep the dahlia plants from becoming too warm in afternoon sunshine. Place the dahlia container outside after all threat of spring frost is past.
Water only enough to keep the dahlia plant from wilting until the plant is 1 foot high. After the plant reaches 1 foot, give a light watering every day to promote more blooming.
Pinch off the top of the center stem down to the first pair of leaves when the dahlia plant has three pairs of leaves. This will encourage the plant to become bushier and not as tall. Pinch off the bottom two pairs of leaves when the dahlia plant is 2 feet tall. This will ensure that adequate air circulates around the bottom of the dahlia plant to prevent mildew.
Fertilize the dahlia plant by mixing the fertilizer with water according to package recommendations for the container size. Fertilize the first time one month after planting. Fertilize a second time one month later.
Remove the spent blossoms after they wither. Use the pruning shears to cut off the bloom one node under the bloom. This will encourage the dahlia plant to continue blooming prolifically on the lateral stems.
Wait until several frosts have occurred and then dig up the dahlia tubers. Trim off all stems and foliage and allow the tubers to dry for approximately one week in a warm place with adequate air ventilation. Place the tubers in a brown grocery bag and cover them with peat moss. Fold the bag closed and store the bag in a location with temperatures between 40 and 50 degrees F.
Replant the tubers again in the spring.